Add enthalpy-based secondary boil-off and turbine mapping

src/reactor_sim/state.py

@@ -4,6 +4,8 @@ from __future__ import annotations
 
 from dataclasses import dataclass, field, asdict
 
+from . import constants
+
 from .generator import GeneratorState
 
 
@@ -51,6 +53,7 @@ class CoolantLoopState:
     steam_quality: float  # fraction of vapor
     inventory_kg: float = 0.0  # bulk mass of coolant
     level: float = 1.0  # fraction full relative to nominal volume
+    energy_j: float = 0.0  # stored thermal/latent energy for the loop
 
     def average_temperature(self) -> float:
         return 0.5 * (self.temperature_in + self.temperature_out)
@@ -135,8 +138,8 @@ class PlantState:
         delta_t = data.get("primary_to_secondary_delta_t", 0.0)
         return cls(
             core=CoreState(**core_blob, fission_product_inventory=inventory, emitted_particles=particles),
-            primary_loop=CoolantLoopState(**data["primary_loop"]),
-            secondary_loop=CoolantLoopState(**data["secondary_loop"]),
+            primary_loop=CoolantLoopState(**_with_energy(data["primary_loop"])),
+            secondary_loop=CoolantLoopState(**_with_energy(data["secondary_loop"])),
             turbines=turbines,
             primary_pumps=[PumpState(**p) for p in prim_pumps_blob],
             secondary_pumps=[PumpState(**p) for p in sec_pumps_blob],
@@ -146,3 +149,14 @@ class PlantState:
             primary_to_secondary_delta_t=delta_t,
             time_elapsed=data.get("time_elapsed", 0.0),
         )
+
+
+def _with_energy(loop_blob: dict) -> dict:
+    """Backwards compatibility: derive energy if missing."""
+    if "energy_j" in loop_blob:
+        return loop_blob
+    energy = 0.5 * (loop_blob.get("temperature_in", 295.0) + loop_blob.get("temperature_out", 295.0))
+    energy *= loop_blob.get("inventory_kg", 0.0) * constants.COOLANT_HEAT_CAPACITY
+    out = dict(loop_blob)
+    out["energy_j"] = energy
+    return out